The present invention relates to a random number sequence sharing system, random number sequence sharing apparatus, codec system, coding apparatus, decoding apparatus, random number sequence sharing method, coding method, and decoding method utilizing a radio wave emitted from a radio star, and a program for realizing these on a computer.
Conventionally, in the field of information communication technologies, researches have been made into authentication technologies for checking message generators or message senders. Currently, signature authentication systems or coded communication systems utilizing public key coding are becoming popular.
Meanwhile, attempts are made to receive a radio wave emitted from radio stars such as quasi-stellar objects (quasars), maser sources (including water maser sources, ammonia maser sources, and methanol maser sources), etc. by VLBI (Very Long Baseline Interferometry), and utilize the received radio wave in various technological fields. Particularly, a signal received by VLBI has an ideal perfect randomness, and a radio wave from a radio star can be received at any geographical point on the earth (or depending on the kind of a radio star, at any geographical point existing on the surface, of the earth's ground surface, that faces this radio star).
Therefore, technologies for measuring a relative positional relation between a point and another point on the earth by utilizing VLBI are put into practical use.
The inventors of the present invention have already proposed an authentication system, etc. utilizing a radio star, in view of demands in the field of information communication, for authentication technologies ensuring higher security that can prevent “pretending”.
Other than the proposal by the inventors, the following documents can be raised as prior art documents.
[Patent Document 1] Unexamined Japanese Patent Application KOKAI Publication No. 2003-218866
[Patent Document 2] Unexamined Japanese Patent Application KOKAI Publication No. 2001-308845
[Patent Document 3] Unexamined Japanese Patent Application KOKAI Publication No. 2000-278259
[Patent Document 4] Unexamined Japanese Patent Application KOKAI Publication No. H11-243313
[Patent Document 1] discloses an authentication system, etc. similar to that disclosed by the inventors. That is, the document discloses a technique in which an authentication apparatus and an authentication target apparatus observe a radio wave from the same radio star at the same observation time, estimate the position of the other apparatus based on the information on the radio wave observed by the other, and authenticate the other as valid in a case where the estimated position and a pre-stored position correspond to each other within a predetermined error range.
[Patent Document 2] discloses a coding technique utilizing stream cipher, which is hard to decipher. That is, a random number sequence is generated based on a given multiple affine key, and the clear text is coded by the exclusive OR of the generated random number sequence and the clear text. The multiple affine key is automatically and sequentially rewritten into a new sequence of multiple affine key, after the multiple affine key is used each predetermined number of times. A random number sequence is newly generated based on the new sequence of multiple affine key, and the clear text after the rewriting of the key is coded by using the newly generated random number sequence.
[Patent Document 3] discloses a data distribution system which distributes sophisticated data to a specific user. That is, a coding process unit reads out distribution target data stored in a data storage unit, affixes a secret key read from a secret key writing process unit to the data, and codes the data by using another secret key read from the secret key writing process unit, while a decoding process unit decodes received data which is coded, by using a secret key which is affixed to previously received data and retained in a secret key retention unit.
[Patent Document 4] discloses a technique for a radio telescope, whose technique relates to relative VLBI for measuring the position of an observation target astronomical object, as a value relative to a reference astronomical object whose position is already known. That is, this technique allows only one antenna to conduct relative VLBI observation, by using a radio telescope capable of relative VLBI observation, to track an astronomical object correspondingly to the earth's rotation on its axis, while at the same time to track an observation target astronomical object for a predetermined time, then quickly change the tracking direction to track the astronomical object for a predetermined time, and again quickly change the tracking direction to track the observation target astronomical object and repeat this operation.
In the field of information communication utilizing coding, there is a strong demand for a technique that allows the coder side and the decoder side to safely share a random number sequence and perform coding and decoding by using this random number sequence.
The present invention is intended for solving the above-described problem, and an object of the present invention is to provide a random number sequence sharing system, random number sequence sharing apparatus, codec system, coding apparatus, decoding apparatus, random number sequence sharing method, coding method, and decoding method utilizing a radio wave emitted from a radio star, and a program for realizing these on a computer.